If you land on time at 5.55 you are very unlikely to be at OKW before 7.30 or 8 pm. Add on another 30 minutes to check in, get your things to your room, freshen up and go and wait for a bus and you are pushing towards 9 pm. Then you still need to get to the park. Assuming you haven't eaten at the resort as you won't really have had time, when you get to MK (Epcot is probably not going to happen). Now you are hungry and fiddling with finding some CS. It is really a waste of a park entrance, unless you have more days on your ticket than days at the parks.
Quite honestly, I would hop on the boat from OKW and head for DTD. Have a nice dinner, walk around and come back when you are ready. You will have a good sleep and getting up early the next morning to be at a park for opening time will see you achieve 5x more in the first hour than you will if you arrive at MK in the evening.
We were due into MCO at 5.55 pm last year. We had always landed early afternoon before. Our flight was delayed so we only landed after 6.30 pm. We sailed through customs with no wait, our luggage was amongst the first off the carousel, I know MCO well enough that we went straight through to magical express with our luggage and found our bus waiting. We departed within 5 minutes of boarding. Despite all this in our favour it was past 8 pm by the time we got to our room. We usually go to DTD on our arrival night but last year we skipped that even. I am a late night person and so is my DD but we just didn't have the energy to go out.
